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<pre><span class="sourceLineNo">001</span><a name="line.1"></a>
<span class="sourceLineNo">002</span>/*<a name="line.2"></a>
<span class="sourceLineNo">003</span> * Copyright (C) 2014 Archie L. Cobbs. All rights reserved.<a name="line.3"></a>
<span class="sourceLineNo">004</span> *<a name="line.4"></a>
<span class="sourceLineNo">005</span> * $Id: BoundaryInputParser.html 5 2014-12-10 22:27:01Z archie.cobbs $<a name="line.5"></a>
<span class="sourceLineNo">006</span> */<a name="line.6"></a>
<span class="sourceLineNo">007</span><a name="line.7"></a>
<span class="sourceLineNo">008</span>package org.dellroad.msrp.msg;<a name="line.8"></a>
<span class="sourceLineNo">009</span><a name="line.9"></a>
<span class="sourceLineNo">010</span>import java.io.ByteArrayOutputStream;<a name="line.10"></a>
<span class="sourceLineNo">011</span>import java.util.regex.Pattern;<a name="line.11"></a>
<span class="sourceLineNo">012</span><a name="line.12"></a>
<span class="sourceLineNo">013</span>import org.dellroad.msrp.MsrpConstants;<a name="line.13"></a>
<span class="sourceLineNo">014</span><a name="line.14"></a>
<span class="sourceLineNo">015</span>/**<a name="line.15"></a>
<span class="sourceLineNo">016</span> * Parses body content bytes separated by MSRP end-line boundaries.<a name="line.16"></a>
<span class="sourceLineNo">017</span> *<a name="line.17"></a>
<span class="sourceLineNo">018</span> * &lt;p&gt;<a name="line.18"></a>
<span class="sourceLineNo">019</span> * Instances are not thread safe.<a name="line.19"></a>
<span class="sourceLineNo">020</span> * &lt;/p&gt;<a name="line.20"></a>
<span class="sourceLineNo">021</span> */<a name="line.21"></a>
<span class="sourceLineNo">022</span>public class BoundaryInputParser {<a name="line.22"></a>
<span class="sourceLineNo">023</span><a name="line.23"></a>
<span class="sourceLineNo">024</span>    private final byte[] terminator;        // terminator string (with variable flag byte)<a name="line.24"></a>
<span class="sourceLineNo">025</span>    private final int flagOffset;           // offset of flag byte in terminator<a name="line.25"></a>
<span class="sourceLineNo">026</span><a name="line.26"></a>
<span class="sourceLineNo">027</span>    private boolean boundary = true;        // whether we are between body parts<a name="line.27"></a>
<span class="sourceLineNo">028</span>    private int matched;                    // how many bytes of terminator we have matched so far<a name="line.28"></a>
<span class="sourceLineNo">029</span><a name="line.29"></a>
<span class="sourceLineNo">030</span>    /**<a name="line.30"></a>
<span class="sourceLineNo">031</span>     * Constructor.<a name="line.31"></a>
<span class="sourceLineNo">032</span>     *<a name="line.32"></a>
<span class="sourceLineNo">033</span>     * @param transactionId transaction ID<a name="line.33"></a>
<span class="sourceLineNo">034</span>     * @throws IllegalArgumentException if {@code transactionId} is null or invalid<a name="line.34"></a>
<span class="sourceLineNo">035</span>     */<a name="line.35"></a>
<span class="sourceLineNo">036</span>    public BoundaryInputParser(String transactionId) {<a name="line.36"></a>
<span class="sourceLineNo">037</span><a name="line.37"></a>
<span class="sourceLineNo">038</span>        // Sanity check<a name="line.38"></a>
<span class="sourceLineNo">039</span>        if (transactionId == null)<a name="line.39"></a>
<span class="sourceLineNo">040</span>            throw new IllegalArgumentException("null transactionId");<a name="line.40"></a>
<span class="sourceLineNo">041</span>        if (!Pattern.compile(Util.IDENT_REGEX).matcher(transactionId).matches())<a name="line.41"></a>
<span class="sourceLineNo">042</span>            throw new IllegalArgumentException("illegal transactionId");<a name="line.42"></a>
<span class="sourceLineNo">043</span><a name="line.43"></a>
<span class="sourceLineNo">044</span>        // Build byte sequence that ends the body (note, the '?' is a placeholder for the flag byte)<a name="line.44"></a>
<span class="sourceLineNo">045</span>        this.terminator = (Util.CRLF + MsrpConstants.END_LINE_PREFIX + transactionId + "?" + Util.CRLF).getBytes(Util.UTF8);<a name="line.45"></a>
<span class="sourceLineNo">046</span>        this.flagOffset = 2 + MsrpConstants.END_LINE_PREFIX.length() + transactionId.length();<a name="line.46"></a>
<span class="sourceLineNo">047</span>        assert terminator[flagOffset] == (byte)'?';<a name="line.47"></a>
<span class="sourceLineNo">048</span>    }<a name="line.48"></a>
<span class="sourceLineNo">049</span><a name="line.49"></a>
<span class="sourceLineNo">050</span>    /**<a name="line.50"></a>
<span class="sourceLineNo">051</span>     * Input the next byte and get back any new content bytes that have been determined to not be part of the boundary string.<a name="line.51"></a>
<span class="sourceLineNo">052</span>     *<a name="line.52"></a>
<span class="sourceLineNo">053</span>     * @param b input byte<a name="line.53"></a>
<span class="sourceLineNo">054</span>     * @return zero or more additional body bytes, or null if the boundary string has been seen<a name="line.54"></a>
<span class="sourceLineNo">055</span>     * @throws ProtocolException if the body exceeds the maximum allowed length<a name="line.55"></a>
<span class="sourceLineNo">056</span>     */<a name="line.56"></a>
<span class="sourceLineNo">057</span>    public byte[] inputContentByte(byte b) {<a name="line.57"></a>
<span class="sourceLineNo">058</span><a name="line.58"></a>
<span class="sourceLineNo">059</span>        // No longer at boundary<a name="line.59"></a>
<span class="sourceLineNo">060</span>        this.boundary = false;<a name="line.60"></a>
<span class="sourceLineNo">061</span><a name="line.61"></a>
<span class="sourceLineNo">062</span>        // Does this byte match the next terminator prefix byte? Note special case for flag byte.<a name="line.62"></a>
<span class="sourceLineNo">063</span>        if (matched == this.flagOffset ?<a name="line.63"></a>
<span class="sourceLineNo">064</span>          b == MsrpConstants.FLAG_INCOMPLETE || b == MsrpConstants.FLAG_COMPLETE || b == MsrpConstants.FLAG_ABORT :<a name="line.64"></a>
<span class="sourceLineNo">065</span>          b == this.terminator[matched]) {<a name="line.65"></a>
<span class="sourceLineNo">066</span><a name="line.66"></a>
<span class="sourceLineNo">067</span>            // Replace '?' with the actual flag seen when we see it<a name="line.67"></a>
<span class="sourceLineNo">068</span>            if (this.matched == this.flagOffset)<a name="line.68"></a>
<span class="sourceLineNo">069</span>                this.terminator[this.flagOffset] = b;<a name="line.69"></a>
<span class="sourceLineNo">070</span><a name="line.70"></a>
<span class="sourceLineNo">071</span>            // Increment the number of terminator bytes matched; have we now matched the entire terminator?<a name="line.71"></a>
<span class="sourceLineNo">072</span>            if (++this.matched == this.terminator.length) {<a name="line.72"></a>
<span class="sourceLineNo">073</span>                this.reset();<a name="line.73"></a>
<span class="sourceLineNo">074</span>                return null;<a name="line.74"></a>
<span class="sourceLineNo">075</span>            }<a name="line.75"></a>
<span class="sourceLineNo">076</span><a name="line.76"></a>
<span class="sourceLineNo">077</span>            // End line not fully matched yet, and there is no additional data at this point<a name="line.77"></a>
<span class="sourceLineNo">078</span>            return new byte[0];<a name="line.78"></a>
<span class="sourceLineNo">079</span>        }<a name="line.79"></a>
<span class="sourceLineNo">080</span><a name="line.80"></a>
<span class="sourceLineNo">081</span>        // Were any bytes previously matched? If not, this is easy.<a name="line.81"></a>
<span class="sourceLineNo">082</span>        if (this.matched == 0)<a name="line.82"></a>
<span class="sourceLineNo">083</span>            return new byte[] { b };<a name="line.83"></a>
<span class="sourceLineNo">084</span><a name="line.84"></a>
<span class="sourceLineNo">085</span>        // Match failure: roll back to the next longest prefix (this is O(n^2)... better would be Knuth-Morris-Pratt variant)<a name="line.85"></a>
<span class="sourceLineNo">086</span>        final ByteArrayOutputStream buf = new ByteArrayOutputStream(this.terminator.length);<a name="line.86"></a>
<span class="sourceLineNo">087</span>        buf.write(this.terminator[0]);<a name="line.87"></a>
<span class="sourceLineNo">088</span>    retractionLoop:<a name="line.88"></a>
<span class="sourceLineNo">089</span>        for (int offset = 1; this.matched &gt; 0; offset++) {<a name="line.89"></a>
<span class="sourceLineNo">090</span><a name="line.90"></a>
<span class="sourceLineNo">091</span>            // Check whether terminator[offset..end] + b matches a prefix<a name="line.91"></a>
<span class="sourceLineNo">092</span>            for (int i = 0; i &lt; this.matched; i++) {<a name="line.92"></a>
<span class="sourceLineNo">093</span>                final byte next = (i &lt; this.matched - 1) ? terminator[offset + i] : b;<a name="line.93"></a>
<span class="sourceLineNo">094</span>                if (terminator[i] != next) {<a name="line.94"></a>
<span class="sourceLineNo">095</span>                    buf.write(--this.matched &gt; 0 ? this.terminator[offset] : b);<a name="line.95"></a>
<span class="sourceLineNo">096</span>                    continue retractionLoop;<a name="line.96"></a>
<span class="sourceLineNo">097</span>                }<a name="line.97"></a>
<span class="sourceLineNo">098</span>            }<a name="line.98"></a>
<span class="sourceLineNo">099</span>            break;<a name="line.99"></a>
<span class="sourceLineNo">100</span>        }<a name="line.100"></a>
<span class="sourceLineNo">101</span><a name="line.101"></a>
<span class="sourceLineNo">102</span>        // Return available bytes<a name="line.102"></a>
<span class="sourceLineNo">103</span>        return buf.toByteArray();<a name="line.103"></a>
<span class="sourceLineNo">104</span>    }<a name="line.104"></a>
<span class="sourceLineNo">105</span><a name="line.105"></a>
<span class="sourceLineNo">106</span>    /**<a name="line.106"></a>
<span class="sourceLineNo">107</span>     * Determine whether this instance is sitting at a content boundary.<a name="line.107"></a>
<span class="sourceLineNo">108</span>     *<a name="line.108"></a>
<span class="sourceLineNo">109</span>     * &lt;p&gt;<a name="line.109"></a>
<span class="sourceLineNo">110</span>     * This will be true after initial construction, invocation of {@link #reset},<a name="line.110"></a>
<span class="sourceLineNo">111</span>     * or an invocation {@link #inputContentByte inputContentByte()} that returned a null value.<a name="line.111"></a>
<span class="sourceLineNo">112</span>     * &lt;/p&gt;<a name="line.112"></a>
<span class="sourceLineNo">113</span>     */<a name="line.113"></a>
<span class="sourceLineNo">114</span>    public boolean isOnBoundary() {<a name="line.114"></a>
<span class="sourceLineNo">115</span>        return this.boundary;<a name="line.115"></a>
<span class="sourceLineNo">116</span>    }<a name="line.116"></a>
<span class="sourceLineNo">117</span><a name="line.117"></a>
<span class="sourceLineNo">118</span>    /**<a name="line.118"></a>
<span class="sourceLineNo">119</span>     * Reset parse state.<a name="line.119"></a>
<span class="sourceLineNo">120</span>     */<a name="line.120"></a>
<span class="sourceLineNo">121</span>    public void reset() {<a name="line.121"></a>
<span class="sourceLineNo">122</span>        this.boundary = true;<a name="line.122"></a>
<span class="sourceLineNo">123</span>        this.matched = 0;<a name="line.123"></a>
<span class="sourceLineNo">124</span>    }<a name="line.124"></a>
<span class="sourceLineNo">125</span><a name="line.125"></a>
<span class="sourceLineNo">126</span>    /**<a name="line.126"></a>
<span class="sourceLineNo">127</span>     * Get the flag byte that was found in the boundary string.<a name="line.127"></a>
<span class="sourceLineNo">128</span>     *<a name="line.128"></a>
<span class="sourceLineNo">129</span>     * &lt;p&gt;<a name="line.129"></a>
<span class="sourceLineNo">130</span>     * If the complete boundary string has not yet been encountered, then the return<a name="line.130"></a>
<span class="sourceLineNo">131</span>     * value from this method is undefined.<a name="line.131"></a>
<span class="sourceLineNo">132</span>     * &lt;/p&gt;<a name="line.132"></a>
<span class="sourceLineNo">133</span>     */<a name="line.133"></a>
<span class="sourceLineNo">134</span>    public byte getFlagByte() {<a name="line.134"></a>
<span class="sourceLineNo">135</span>        return this.terminator[this.flagOffset];<a name="line.135"></a>
<span class="sourceLineNo">136</span>    }<a name="line.136"></a>
<span class="sourceLineNo">137</span>}<a name="line.137"></a>
<span class="sourceLineNo">138</span><a name="line.138"></a>




























































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